[Search for users] [Overall Top Noters] [List of all Conferences] [Download this site]

Conference napalm::guitar

Title:GUITARnotes - Where Every Note has Emotion
Notice:Discussion of the finer stringed instruments
Moderator:KDX200::COOPER
Created:Thu Aug 14 1986
Last Modified:Fri Jun 06 1997
Last Successful Update:Fri Jun 06 1997
Number of topics:3280
Total number of notes:61432

2292.0. "Reverb problem....help!!" by MEMORY::RATTEY () Mon Aug 12 1991 17:01

        
    	I've got problem with the Reverb section of my Super Reverb...
    	Symptoms are ...no reverb....what I've checked, so far,  
    	with my limited equipment(ohm meter) is...
    	
    	- I've changed the reverb preamp tube (12AT7 or 12AX7 ??)
    
    	- i check the x-former in the reverb section..it shows about
    	   2k-ohms on the output winding..is this ok ??
           input winding are very low dc resistance.
    
     	- I'm really suspecting the reverb tank.....I'm not 100%  sure 
    	   ...but I was expecting to be able to read a dc resistance
    	   from input to output jack...it reads open.......
    
    	....so does it sound like the x-former or the reverb tank????
    
    
    	any other suggestions???
    	  
    
    
    
    	Ray.
T.RTitleUserPersonal
Name
DateLines
2292.1FREEBE::REAUMESIzzLE on SiXMon Aug 12 1991 17:287
        I'm not a wiz on spring reverbs, but: I don't think 2K on the 
    output winding is too cool (it might be your problem!). There is 
    no electrical connection from the input to the output on the reverb
    tank. The transducers on each end of the spring should be isolated. 
    
    
    							-B()()M-
2292.2RAVEN1::BLAIRNeed a hot tune and a cold oneMon Aug 12 1991 18:164
    
    	
    When I lost the reverb on my KH (also spring), it turned out to be the
    1458-type op-amp chip.
2292.3MIcro Mho's...AKOV05::DERRICOSet Weekend=RELAX_ONTue Aug 13 1991 11:0913
    Ray,
    
       You should not read anything from the input of the reverb to the
    output of the reverb. spring reverbs are set up like two phono pickups
    with a spring in the middle - there is a send transformer at one end,
    and a receive transformer at ther other. The springs are isolated from
    both ends.
      When you ohm out each coil, they may or may not be the same impedance.
    The 2-K value might be good since it's probably a hi-impedance circuit.
    I'm "guessing" that you should not read any thing lower than 150 ohms,
    and no higher than 50-k.
    
    /J
2292.4MEMORY::RATTEYTue Aug 13 1991 11:5510
    
 
    
    	Yah...I ohmed out the transformers internel to the reverb...one
    	seemed ok but the other seemed to be open....I think I might 
    	try it again with a better meter though..the one I was using 
    	was one of those 19.95 Rat Shack specials..the bat. is
    	probably half dead too...I'll check it out again tonight....
    	....hopefully my fender mender will be in tonight so can
    	screw around with that too....
2292.5looking for reverb tank....MEMORY::RATTEYWed Aug 14 1991 17:3522
    
    	I'll enter this info in case anyone decides to get their hands
    	into the reverb section of a super (probably applies to most other
    	fender amps)...this info came from the service dept at fender...
    
    	DC resistancd of transformer(TR4) in reverb driver circuit:
    	input winding(red+blue) = 2k-ohms
    	output winding(grn+blk) = low ohms (1-2 ohms)
    	
    	DC resistance of transducers inside reverb tank:
    	inout = low ohms
    	output = 160 ohms
     
    	the coils internal to the tank are isolated from the transducers....
    	you will not read any resistance from inout to output jacks
    	on the tank....
    	
    
        anyone got an old reverb tank hanging around collecting dust ????
    	
    
    Ray
2292.6The mad doctor strikes again......TRUCKS::LITTENThu Aug 15 1991 16:0538
    
Ray,

	I have had some problems with spring reverbs in the past.

The sort Fender use are made by Accutronics in the US.

I have had the coils blow on them (to be precise, the coil connections as 
they emerged from the winding got fatigued due to vibration over time and 
broke).

I managed to "gently" solder it back. Also the springs sometimes broke and I 
again, re-soldered them back to working order.

IF I got real desperate, I guess I would try and re-wind the sucker, although
I have yet to try......

The accutronics units are available here in the UK at about 30 pounds sterling
....(about 50 dollars?), so you could look on the unit for their address, 
find a local supplier ( your music shop?), and order one.

BTW, I am guessing here, but if you have a real sensitive (1 millivolt range
meter), you could GENTLY "scratch" the spring with the meter hung across the
output coil. You should get a reading on ac volts. This would only test the 
output transducer.

If you want to get real clever.....Your input transducer has an impedance
of 2K ohms, so hang a small torch battery (about 1 1/2 volts) across it for
a fraction of a second (perhaps put a 1K ohm resistor in series to limit
the transient current to about 1/2 mA). Put your ear to the reverb spring
and you should hear a "reverby" click. These two tests have confirmed the
reverb is functioning and the problem may be in the connectors or drive/amp
circuitry.

Good luck,

Dave "analog" Litten
 
2292.7Fender reverb tank ~$30LEDS::ORSICuz I felt like it....OK!?!!Fri Aug 16 1991 11:0911
    	Ray, the Cambridge Music Center in Porter Sq., Cambridge
    	has new Fender reverb tanks for ~$30.

    			Cambridge Music Center
    			1904 Mass Ave.
    			Cambridge, MA
    			(617) 491-5433 ask for Hal
    
    	Neal
    
2292.8AccutronicsSMURF::BENNETTAsk me about Guitar LessonsFri Aug 16 1991 19:463
	Aren't they also known as Morley?

2292.9DNEAST::GREVE_STEVEGreee Veee KingMon Aug 19 1991 13:023
    
    
    	have you ohmed out the  cables???
2292.10MEMORY::RATTEYMon Aug 19 1991 13:088
    
    
    	Yah..cables look fine....the problem appears to be one of the
    	transducers internal to the tank...one reads open....
    
    	now if I could only find where that little wire is broken....
    
    
2292.11Coiley's a wise guy...GIAMEM::DERRICOSet Weekend=RELAX_ONTue Aug 20 1991 14:417
    Ray,
    
       If you haven't already, remove the reverb from the amp. Check
    the solder job on the RCA jack. If you've already had it out, just
    rewind the coil... *8^)) (Just kidding!).
    
    /J
2292.12Sorry I'm lateFREEBE::LOUVATWed Jan 08 1992 11:357
    For the life of me I don't know why anyone would want to mess around
    with a spring reverb....especially after experiencing a good digital
    reverb. There is no comparison. I've got a peavey reverb pedal and it
    has to be the best reverb effect I've ever heard for the price.........
    (and it is stereo and totally quiet. plus it has 16 different select-
    ions to chose from ranging from a lush hall to reverse gating).........
    Simply amazing!!!
2292.13Need reverb help!!SAHQ::ROSENKRANZGo ask Alice....Mon Mar 14 1994 11:2612
    I've got a bit of a problem with the reverb on a 66 Princeton reverb.
    Typically, when I turn the amp on, the reverb doesn't work at all. 
    However, if I turn the volume up, and strum a big loud chord, it seems
    to "wake it up", and then it subsequently works fine, for as long as
    I use it.
    
    Does anyone have any ideas on what is happening here, and how I might
    permanently fix this annoying (but not life threatening) problem??
    
    thanks,
    
    jim
2292.14Seen that beforeLEDS::ORSIKinfolk said..move away from thereMon Mar 14 1994 12:0510
     Jim,

     It's most likely V2. (12AT7 reverb driver tube). I'd recommend
     swapping it out with a known good tube. If not ok, swap out V3
     (12AX7 reverb recovery and 3rd gain stage tube). If still not ok,
     it's probably the reverb tank. They're ~$30.

     Neal